The present invention relates to engine system operation, and more particularly to identifying fuel dynamical steady state (FDSS) of an engine system.
Automotive engines are complex dynamic systems. Performance of the engine is influenced by a number of parameters such as fuel offset, commanded fuel, actual fuel, commanded mass of air, actual mass of air and/or other parameters. The engine parameters are monitored to evaluate and adjust engine performance. The engine parameters provide observable engine system characteristics. Observation of the engine characteristics enables more accurate operation and control of the engine.
Fuel dynamical steady state (FDSS) presents a special operating condition of the engine. FDSS is an engine state during which measured fuel is nearly constant except for relatively small periodic fluctuations, which are a characteristic of fuel feedback control systems. Traditional monitoring systems do not identify FDSS during operation of the engine. As a result, observable engine characteristics are lost.
Accordingly, the present invention provides an engine control system that identifies fuel dynamical steady state FDSS. The engine control system includes an engine having one or more cylinders and a controller that sets a detection period. The controller monitors a mass of fuel ingested by the cylinder during the detection period. The controller identifies FDSS if the mass of fuel remains within a predetermined range during the detection period.
In one feature, the mass of fuel is a measured mass of fuel. Alternatively, the mass of fuel is a commanded mass of fuel.
In another feature, the controller monitors an air to fuel (A/F) ratio within the cylinder and monitors a mass of air ingested by the cylinder. The mass of fuel is based on the A/F ratio and the mass of air ingested by the cylinder.
In still another feature, the controller determines an average mass of fuel for the detection period. The predetermined range is based on the average mass of fuel. The predetermined range includes a lower limit based on the average mass of fuel and a steady state threshold. The predetermined range includes an upper limit based on the average mass of fuel and a steady state threshold.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.